The present invention relates broadly to an apparatus and method for controlling electrically powered pumps for liquids and is more specifically concerned with an apparatus and method for controlling the operations of bilge or sump pumps.
In a typical bilge pump installation the pump, powered by a fractional horsepower d.c. electric motor, is located at a low point in the bilge of the vessel and is wired to an appropriate source of electric power therefor, such as a battery or, in the case of power boats having electrical power generating capacity, to the electrical system of the boat. While control of the operation of such a pump may be undertaken manually, such as by the installation of a manually operated switch in the power supply circuit to the pump motor, it is usually desired that the pump be controlled automatically in response to water level changes in the bilge. To this end, various float switches are conventionally employed to control bilge pump operations, said switches broadly comprising a fixed base member and a float member which is usually, but not universally, pivotally attached to the base member. The float member carries a switching element, such as a mercury capsule, which is wired in series into the power supply circuit to the pump motor and which is responsive to the position of the float member relative to the base member. Such float switch devices are necessarily located in the bilge. In consequence of this arrangement, the switching element automatically makes or breaks the power supply circuit to the pump as a function of the position of the float member relative to the base member. Unfortunately, the bilges of vessels are normally dirty and often include chemicals such as cleansers, oils and greases as well as such solid particulates and fibrous adulterants as sand, grit, shells, fish scales, cordage, fishing line, paper and the like. Accordingly, the typical bilge environment is extremely hostile to long term good operations of float switches which depend for their effectiveness upon the maintenance of free motion between the float member and the fixed base member.
Another pump control system which has been attempted to be utilized in the automatic control of bilge pumps comprises a pair of electrically conductive low and high water sensing probes which are appropriately positioned in the bilge, said probes being wired, through appropriate circuitry, into the power supply circuit to the bilge pump. Such a bilge pump control system is described, for instance, in U.S. Pat. No. 4,171,932, Gerald K. Miller, Oct. 23, 1979. By suitable adjustment of the high and low water sensing probes within the bilge, the bilge water, at its high level, immerses both probes, thereby establishing a low resistance bridge therebetween and causing the closure of the pump motor power supply circuit. As the pump removes water from the bilge the water level therein decreases to the point where there is ultimately attained a condition wherein neither probe is continuously immersed in the bilge water. At this point both probes signal a high resistance condition and the power supply circuit to the pump motor is opened until such time as the accumulation of water in the bilge is again sufficient to immerse both probes. Again, however, this system depends upon immersion of the sensing probes in the bilge water and, because the bilge water is usually dirty, said probes can quickly become sufficiently fouled as to markedly alter their resistance sensing properties, thereby to adversely affect their desired pump control function.
Pump control apparatuses essentially similar to those broadly described above in reference to bilge pump control are also utilized in controlling sump pumps such as are conventionally employed to remove groundwater and seepage from foundations and cellars. Such pumps are normally driven by a.c. motors. Similar problems as those outlined above also attend sump pump control operations.
In accordance with the present invention, however, there is provided a pump control apparatus which may be connected at any convenient location along the pump motor power supply circuit and which apparatus may be located in its entirety outside the immediate environment of the liquid to be pumped.
There is also provided a novel pump/pump control system or combination wherein the pump control component is physically separate and remote from the pump component, or wherein the pump control component is physically integrated with the pump component.